Masayoshi Takayanagi

• Dr. (Information Science)
• Professor (Associate) at Shiga University

In the semiconductor manufacturing process, the miniaturization of patterns has led to increased structural fragility, making pattern collapse a critical issue during the drying step in wet cleaning processes. Such collapse can lead to device defects, which must be avoided. One method to prevent pattern collapse is surface modification treatment (S...

Since the pattern collapse was reported for the first time it has been getting more critical issue in wet cleaning process along with semiconductor scaling. The model of the pattern collapse is that structures such as fins deform due to capillary force during drying step, then they contact and stick each other due to surface tension. One technique...

As the semiconductor industry relentlessly reduces device sizes, efficient and precise cleaning processes have become increasingly critical to address challenges such as nanostructure stiction. Gaining insight into the molecular behavior of water and isopropyl alcohol (IPA) on silicon dioxide (SiO2) surfaces is essential for controlling semiconduct...

Radical polymerization is an economic and practical polymerization method over ionic and coordination polymerizations and is widely used for polymer production. Although many efforts have been made to improve the convenience and controllability of radical polymerization, it is still a challenge to directly observe the microbehaviors of propagation,...

The demand for the autonomous adaptive control of manufacturing lines has been growing to realize productivity improvement and carbon neutrality. We propose a methodology to realize the autonomous control of product quality under the existence of effects from non-measurable parameters. By local linear regression modeling with temporal neighborhood...

The purification step in the manufacturing of cyclic polymers is difficult as complete fractionation to eliminate linear impurities requires considerable effort. Here, we report a new polymer separation methodology that uses metal‐organic frameworks (MOFs) to discriminate between linear and cyclic polyethylene glycols (PEGs) via selective polymer i...

Free radical polymerization is a critical route for generating vinyl polymers owing to its versatility and productivity, while the realization of stereospecific propagation has been considered very difficult and demanding. Therefore, a concrete investigation on the mechanism of tacticity obtained in radical polymerization is urgent. Experimentally,...

Graphene nanoribbons (GNRs), narrow and straight-edged stripes of graphene, attract a great deal of attention because of their excellent electronic and magnetic properties. As of yet, there are no fabrication method for GNRs to satisfy both precision at the atomic-scale and scalability, which is critical for fundamental research and future technolo...

A new efficient Red Moon methodology and its related applications are reviewed. First, the motivation to develop this new computational molecular technology (CMT) is introduced in general from the viewpoint of the recent necessity to perform “atomistic” molecular simulation of the large‐scale and long‐term phenomena of (i) complex chemical reaction...

We have realized the microscopic simulation of olefin polymerization, that is, the simulation of the catalytic polymerization (CP) reaction system composed of (pyridylamido)hafnium(IV) complex as the catalyst. For this purpose, we adopted Red Moon (RM) method, a novel molecular simulation method to simulate the complex reaction system. First, accor...

Separation of high-molecular-weight polymers differing just by one monomeric unit remains a challenging task. Here, we describe a protocol using metal-organic frameworks (MOFs) for the efficient separation and purification of mixtures of polymers that differ only by their terminal groups. In this process, polymer chains are inserted by threading on...

The possibility of coexistence of multiple isomers for zirconium bis(phenoxy-imine) catalyst has been systematically studied by computational approaches. The energetics among the five different isomers of neutral Zr-catalyst have been assessed quantum mechanically. The results suggest that isomer cis-N/trans-O/cis-Me is the most stable among the fi...

The design of monomer sequences in polymers has been a challenging research subject, especially in making vinyl copolymers by free-radical polymerization. Here, we report a strategy to obtain sequence-regulated vinyl copolymers, utilizing the periodic structure of a porous coordination polymer (PCP) as a template. Mixing of Cu2+ ion and styrene-3,5...

We studied the stereoselective propylene polymerization catalyzed by the ion pair (IP) active species of (pyridylamido)hafnium(IV) complex, the catalyst. In particular, we focused on the role of the counteranion (CA) for the reaction mechanism of propylene insertion because it had never been investigated from the molecular point of view. First, we...

We report a molecular dynamics (MD) study on the ion pair [{N⁻,N,C⁻}HfMe][MeB(C6F5)3], which is the active species of a (pyridylamide)hafnium(IV) complex for olefin polymerization. The present simulation model system is composed of an ion pair in explicit organic solvent (heptane) with and without ethylene monomers. MD simulations revealed an activ...

Ring-opening polymerization of lactones initiated by cyclodextrins have been reported as a promising polymer synthetic method. To investigate the unknown molecular level mechanism of the initiation reaction, we executed molecular dynamics simulations of model systems composed of single or multiple β-cyclodextrin ( β-CD) molecules in δ-valerolactone...

Thrombin has been studied as a paradigmatic protein of Na(+)-activated allosteric enzymes. Earlier structural studies suggest that Na(+)-binding promotes the thrombin-substrate association reaction. However, it is still elusive because (1) the structural change, driven by Na(+)-binding, is as small as the thermal fluctuation, and (2) the bound Na(+...

Each subunit of human hemoglobin (HbA) stores an oxygen molecule (O2) in the binding site (BS) cavity near the heme group. The BS is buried in the interior of the subunit so that there is a debate over the O2 entry pathways from solvent to the BS; histidine gate or multiple pathways. To elucidate the O2 entry pathways, we executed ensemble molecula...

The radical polymerization in the channels of porous coordination polymers (PCPs) composed of different dicarboxylate ligands has been reported as a promising approach to control the tacticity of product polymers. However, it is still elusive how the different ligands contribute to control the tacticity. Here we anticipate an important role of the...

Upon protein-substrate association reaction, dewetting of substrate-binding pocket is one of rate-limiting processes. However, understanding the microscopic mechanism still remains challenging because of practical limitation of experimental methodologies. We here addressed the problem by using molecular dynamics (MD) simulation of thrombin-substrat...

Radical polymerization in nanoscale channels of porous coordination polymers has been explored as a promising technique to control the properties of product polymers. In particular, tacticity of poly(methyl methacrylate) was successfully controlled by utilizing one-dimensional channels of [M-2(L)(2)TED](n) type of porous coordination polymers by ch...

The quest for porous coordination polymers (PCPs) has been the subject of intense research because of their unique porous functions. Although considerable attention has been paid to the behavior of gases and low-molecular-weight compounds in PCPs, the study of adsorption, diffusion, and interaction of macromolecules, including oligomers and polymer...

We shed light on important roles of unbound Na(+) molecules in enzymatic activation of thrombin. Molecular mechanism of Na(+)-activation of thrombin has been discussed in the context of allostery. However, the recent challenge to redesign K(+)-activated thrombin revealed that the allosteric interaction is insufficient to explain the mechanism. Unde...

In this study, we demonstrate that U1A-RNA molecular recognition is mediated by a combined mechanism of conformational selection and induced fit. The binding of U1A to RNA has been discussed in the context of induced fit that involves the reorientation of -helix in the C-terminal region (Helix-C) of U1A to permit RNA access only when U1A correctly...

Protein allostery is essential for vital activities. Allosteric regulation of human hemoglobin (HbA) with two quaternary states T and R has been a paradigm of allosteric structural regulation of proteins. It is widely accepted that oxygen molecules (O2) act as a "site-specific" homotropic effector, or the successive O2 binding to the heme brings ab...

The heme oxygen (O2) binding site of human hemoglobin (HbA) is buried in the interior of the protein and there is a debate over the O2 entry pathways from solvent to the binding site. As a first step to understand HbA O2 binding process at the atomic level, we detected all the significant multiple O2 entry pathways from solvent to the binding site...

The incipient structural and vibrational energy relaxation process of photolyzed carbonmonoxy myoglobin was analyzed by the perturbation ensemble molecular dynamics (PEMD) method, in which many pairs of perturbed and unperturbed MD simulations are executed for ensemble-averaging to obtain statistically significant results by canceling out thermal f...

The structural dynamics of the clamshell rotation of photodissociated carbonmonoxy myoglobin, which is expected to be important for hemoglobin allostery, is investigated by the perturbation ensemble method. In this method, many pairs of perturbed and unperturbed molecular dynamics trajectories are ensemble-averaged to cancel out thermal noises and...

The partial molar volume (PMV) of the protein chymotrypsin inhibitor 2 (CI2) was calculated by all-atom MD simulation. Denatured CI2 showed almost the same average PMV value as that of native CI2. This is consistent with the phenomenological question of the protein volume paradox. Furthermore, using the surficial Kirkwood-Buff approach, spatial dis...

名古屋大学博士学位論文 学位の種類:博士(情報科学) (課程) 学位授与年月日:平成21年2月27日

The effectiveness of the ensemble perturbation method, in which many pairs of perturbed and unperturbed molecular dynamics simulations are executed for the ensemble average, has been demonstrated by calculating the subtle anisotropic structural change of carbonmonoxy myoglobin (MbCO) triggered by ligand photolysis. The results show that Mb largely...

Molecular dynamics simulations of N-terminal peptides from apo-myoglobin with several lengths were executed to study their stability to testify the possibility of cotranslational folding. By analyzing 10 ns MD simulations in water, we found that the secondary and tertiary structures of a short N-terminal peptide (36 residues) are unstable whereas t...